A.C. cochlear potentials will be measured in large groups of pigeons all the same age in an effort to determine what physiological and pathological variables in the animals over a two year period can predict the loss or gain of these electric potentials. Two diet conditions will be used for the birds: (1) high cholesterol versus (2) low cholesterol. Two breeds of birds will be used, each having a sub-group on the respective high-low cholesterol diets. One breed of pigeon is genetically susceptible to atherosclerosis, the other to be used is genetically resistant. At regular intervals for two years all birds will have blood pressure, blood coagulation, and blood lipid studies. At two years all birds will have their A.C. cochlear potentials measured along with degree of atherosclerosis. A multi-variant statistical analysis will be performed for all the measured variables to determine which, if any, can predict differences in cochlear potentials between groups and individual birds. The birds studied at two years will all be 27 months of age. In a separate study all the same variables will be measured in groups of resistant and susceptible birds of age 3 months--all on a normal low cholesterol diet.